<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }

        body {
            background: url(imgs/你的名字.jpg) no-repeat center top;
        }

        li {
            list-style: none;
        }

        .baidu {
            overflow: hidden;
            margin: 100px auto;
            background-color: #fff;
            width: 410px;
            padding-top: 3px;
        }

        .baidu li {
            float: left;
            margin: 0 1px;
            cursor: pointer;
        }

        .baidu img {
            width: 100px;
        }
    </style>
</head>
<body>
    <ul class="baidu">
        <li><img src="imgs/csgo3.0.png"></li>
        <li><img src="imgs/一人之下.webp"></li>
        <li><img src="imgs/你的名字.jpg"></li>
        <li><img src="imgs/千与千寻.jpg"></li>
    </ul>

    <script>
        // 1. 获取元素
        var imgs = document.querySelector('.baidu').querySelectorAll('img');
        // 2. 循环注册事件
        for(var i = 0 ;i < imgs.length; i++) {
            imgs[i].onclick = function() {
                document.body.style.backgroundImage = 'url('+ this.src +')';
            }
        }

    </script>
    
</body>
</html>